introduce "per task source" ignoring of tasks

components/script/task_source/mod.rs

@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+
 pub mod dom_manipulation;
 pub mod file_reading;
 pub mod history_traversal;
@@ -10,10 +11,33 @@ pub mod performance_timeline;
 pub mod user_interaction;
 
 use dom::globalscope::GlobalScope;
+use enum_iterator::IntoEnumIterator;
 use std::result::Result;
 use task::{TaskCanceller, TaskOnce};
 
+// The names of all task sources, used to differentiate TaskCancellers.
+// Note: When adding a task source, update this enum.
+// Note: The HistoryTraversalTaskSource is not part of this,
+// because it doesn't implement TaskSource.
+#[derive(Eq, Hash, IntoEnumIterator, JSTraceable, PartialEq)]
+pub enum TaskSourceName {
+    DOMManipulation,
+    FileReading,
+    HistoryTraversal,
+    Networking,
+    PerformanceTimeline,
+    UserInteraction
+}
+
+impl TaskSourceName {
+    pub fn all() -> Vec<TaskSourceName> {
+        TaskSourceName::into_enum_iter().collect()
+    }
+}
+
 pub trait TaskSource {
+    const NAME: TaskSourceName;
+
     fn queue_with_canceller<T>(
         &self,
         task: T,
@@ -26,6 +50,7 @@ pub trait TaskSource {
     where
         T: TaskOnce + 'static,
     {
-        self.queue_with_canceller(task, &global.task_canceller())
+        let canceller = global.task_canceller(Self::NAME);
+        self.queue_with_canceller(task, &canceller)
     }
 }